Shielded electrical cables are used as transmission lines, either in round or flat form, to transmit signals through a plurality of conductors which, preferably, are physically separated and electromagnetically isolated along their entire length. Shielded cables presently are used predominantly in relatively high speed applications between various system components in data processing networks, high speed video systems and the like. Coaxial cables are typically used in a singular conductor configurations in high frequency video applications. The lower frequency data transmission lines are often separate from the video signals due to circuit considerations such as impedance, balanced transmission systems and common mode rejection. Generally, improvements in these circuit considerations require relatively large cable and costly construction, neither of which is desirable. In a cable transmitting high frequency signals, it is important to control impedance. It also is important to control cross-talk (internal) between the multiple transmission lines. Still further, it is important to prevent radiation to and from the transmission lines to the outside (external). Achieving such characteristics in a very high density coaxial cable, particularly with the ever-increasing miniaturization of transmission systems, becomes increasingly difficult.
This invention is directed to solving these problems in a hybrid cable design intended for use as a high density multi-channel cable to provide controlled impedance with minimal cross-talk and full shielding against radiated emissions, and particularly in a high density hybrid or mixed cable incorporating high speed transmission lines , such as for a video monitor, as well as twisted pair data transmission lines which have lower bandwidth and therefore slower data speed.